DOCKER INSTALLATION: Can't Connect to MYSQL Server

Product Support Mautic 5 Install/Upgrade Support
1

Your software
My Mautic version is: 5
My PHP version is: 8
My Database type and version is: MYSQL

Your problem
My problem is: Docker installation can’t connect to MYSQL

These errors are showing in the log:
mautic_web-1 | mysqladmin: connect to server at ‘db.farm-mail-docker’ failed
mautic_web-1 | error: ‘Host ‘172.19.0.3’ is not allowed to connect to this MySQL server’
mautic_web-1 | mysqladmin: connect to server at ‘db.farm-mail-docker’ failed
mautic_web-1 | error: ‘Host ‘172.19.0.3’ is not allowed to connect to this MySQL server’
mautic_web-1 | mysqladmin: connect to server at ‘db.farm-mail-docker’ failed
mautic_web-1 | error: ‘Host ‘172.19.0.3’ is not allowed to connect to this MySQL server’
mautic_web-1 | mysqladmin: connect to server at ‘db.farm-mail-docker’ failed
mautic_web-1 | error: ‘Host ‘172.19.0.3’ is not allowed to connect to this MySQL server’
mautic_web-1 | mysqladmin: connect to server at ‘db.farm-mail-docker’ failed
mautic_web-1 | error: ‘Host ‘172.19.0.3’ is not allowed to connect to this MySQL server’

Steps I have tried to fix the problem:
-reviewed config and made sure all the env variables were set
-reviewed old posts for solutions
-reviewed github issues for solutions

My config:

**docker-compose.yml**
x-mautic-volumes:
  &mautic-volumes
  - ./config:/var/www/html/config:z
  - ./logs:/var/www/html/var/logs:z
  - ./media/files:/var/www/html/docroot/media/files:z
  - ./media/images:/var/www/html/docroot/media/images:z
  - ./cron:/opt/mautic/cron:z
  - mautic-docroot:/var/www/html/docroot:z
 
services:
  db:
    image: mysql:8.0
    environment:
      - MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD}
      - MYSQL_DATABASE=${MYSQL_DATABASE}
      - MYSQL_USER=${MYSQL_USER}
      - MYSQL_PASSWORD=${MYSQL_PASSWORD}
    volumes:
      - mysql-data:/var/lib/mysql
    healthcheck:
      test: mysqladmin --user=$$MYSQL_USER --password=$$MYSQL_PASSWORD ping
      start_period: 5s
      interval: 5s
      timeout: 5s
      retries: 10
    networks:
      - default
 
  nginx:
    image: nginx
    volumes:
      - ./nginx.conf:/etc/nginx/conf.d/default.conf
      - mautic-docroot:/var/www/html/docroot:z
    depends_on:
      - mautic_web
    ports:
      - 8002:80
    networks:
      - default
 
  mautic_web:
    image: mautic/mautic:5-fpm
    links:
      - db:mysql
    volumes: *mautic-volumes
 
    environment:
      - DOCKER_MAUTIC_LOAD_TEST_DATA=${DOCKER_MAUTIC_LOAD_TEST_DATA}
      - DOCKER_MAUTIC_RUN_MIGRATIONS=${DOCKER_MAUTIC_RUN_MIGRATIONS}
    env_file:
      - .mautic_env
    healthcheck:
      test: cgi-fcgi -bind -connect 192.168.1.125:9000
      start_period: 5s
      interval: 5s
      timeout: 5s
      retries: 100
    depends_on:
      db:
        condition: service_healthy
    networks:
      - default
 
  mautic_cron:
    image: mautic/mautic:5-fpm
    links:
      - db:mysql
    volumes: *mautic-volumes
    environment:
      - DOCKER_MAUTIC_ROLE=mautic_cron
    env_file:
      - .mautic_env
    depends_on:
      mautic_web:
        condition: service_healthy
    networks:
      - default
 
  mautic_worker:
    image: mautic/mautic:5-fpm
    links:
      - db:mysql
    volumes: *mautic-volumes
    environment:
      - DOCKER_MAUTIC_ROLE=mautic_worker
    env_file:
      - .mautic_env
    depends_on:
      mautic_web:
        condition: service_healthy
    networks:
      - default
 
volumes:
  mysql-data:
  mautic-docroot:
 
networks:
  default:
    name: ${COMPOSE_PROJECT_NAME}-docker
 
**.env**
COMPOSE_PROJECT_NAME=farm-mail
COMPOSE_NETWORK=${COMPOSE_PROJECT_NAME}-docker
MYSQL_HOST=db.${COMPOSE_NETWORK}
MYSQL_PORT=3306
MYSQL_DATABASE=mautic_db
MYSQL_USER=evon
MYSQL_PASSWORD=fmq2108b
MYSQL_ROOT_PASSWORD=fmq2108b
DOCKER_MAUTIC_RUN_MIGRATIONS=false
DOCKER_MAUTIC_LOAD_TEST_DATA=false
 
**.mautic_env**
COMPOSE_PROJECT_NAME=farm-mail
COMPOSE_NETWORK=${COMPOSE_PROJECT_NAME}-docker
MYSQL_HOST=db.${COMPOSE_NETWORK}
MYSQL_PORT=3306
MYSQL_DATABASE=mautic_db
MYSQL_USER=evon
MYSQL_PASSWORD=fmq2108b
MYSQL_ROOT_PASSWORD=fmq2108b
DOCKER_MAUTIC_RUN_MIGRATIONS=false
DOCKER_MAUTIC_LOAD_TEST_DATA=false
root@mail-list-server:~/mautic# cat .mautic_env 
# use this file for environment variables that can be used.
# see https://docs.mautic.org/en/5.x/
 
MAUTIC_DB_HOST="${MYSQL_HOST}"
MAUTIC_DB_PORT="${MYSQL_PORT}"
MAUTIC_DB_DATABASE="${MYSQL_DATABASE}"
MAUTIC_DB_USER="${MYSQL_USER}"
MAUTIC_DB_PASSWORD="${MYSQL_PASSWORD}"
 
MAUTIC_MESSENGER_DSN_EMAIL="doctrine://default"
MAUTIC_MESSENGER_DSN_HIT="doctrine://default"